Various position information management systems are being proposed which grasp and manage a position of a wireless terminal, or a person or an article having the wireless terminal in a facility in which an accurate positioning using GPS, etc., is difficult.
Patent document 1 discloses a system in which a passive RF (Radio Frequency) tag attached to a person is read with a fixed RF (Radio Frequency) reader/writer and a position thereof is reported to a different wireless terminal, etc.
Patent document 2 discloses a system in which a wireless terminal converts an identifier which is wirelessly transmitted from a neighboring transmitter to position specifying information to specify an own position.
Patent document 3 discloses a system in which a wireless terminal receives specific information transmitted from a lighting apparatus and transmits the specific information to a server to specify a position of the wireless terminal.
However, with the system in Patent document 1, a large number of RF (Radio Frequency) reader/writers needs to be installed in order to read the passive RF (Radio Frequency) tag with a narrow range in which communications are possible, which may lead to higher cost in implementing the infrastructure.
Moreover, with the system in Patent document 2, power consumption of the wireless terminal may become high depending on a communications scheme between the wireless terminal and a server.
Furthermore, also in the system in Patent document 3, power consumption of the wireless terminal is not taken into account as in Patent document 2. Moreover, in a server, in order to specify the position of the wireless terminal, it is necessary to search a position associated with the specific information, which could lead to a higher computation cost.